Intraocular lens

ABSTRACT

An intraocular lens includes a lens body having a convex front surface and a planar back surface, an integral peripheral ring having an internal bevel extending rearwardly from the back surface, and four holes spaced about and adjacent the periphery of the lens body and extending from the front surface to the back surface. A pair of curved, filament members are attached to the lens body within apertures in bosses formed on the front surface of the lens body. Each filament member includes an inward u-niche and a distal closed loop. The u-niche makes for improved and easier insertion. The distal closed loop helps prevent iris entrapment and rupturing the posterior capsule.

CROSS REFERENCE

This application is a continuation-in-part of my application Ser. No.483,384, filed Apr. 8, 1983 and entitled "Intraocular Lens", nowabandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of intraocular lenses, andmore particularly to an intraocular lens for mounting within theposterior chamber of the eye.

2. Description of the Prior Art

The lens of the human eye is situated behind the pupil and iris andfunctions to focus light entering through the cornea onto the retina atthe rear of the eye. The lens is a biconvex, highly transparentstructure made of ectodermal cells in concentric lamellae surrounded bya thin capsule. The lens capsule is supported at its periphery ofsuspensory ligaments, called zonules, that are continuous with theciliary muscle. Contraction of this muscle relaxes the zonules, allowingthe lens to become more spherical and thereby altering its focal length.

Under certain conditions, it is necessary to surgically remove a portionor all of the lens. For example, a cataract condition results when thematerial within the lens capsule becomes clouded, thereby obstructingthe passage of light through the lens. To correct this condition, twoforms of surgery are used. In intracapsular cataract extraction, theentire lens is removed intact by severing the zonules or suspensoryligaments about the entire periphery of the capsule. In extracapsularcataract extraction, an incision is made through the front wall oranterior capsule of the lens and the clouded cellular material withinthe capsule is removed. The transparent rear wall or posterior capsuleremains in place in the eye, along with the zonules and peripheralportions of the anterior capsule known as the anterior capsule flaps.

Both of these procedures correct the blockage of light caused by thecataract condition. However, the light entering through the cornea andpupil is no longer focused by a lens. A variety of devices andtechniques have been employed over the years to provide a substitute forthe lens that has been removed or effectively destroyed by theintracapsular and extracapsular extractions. Many of these are welldescribed in the prior art selection of U.S. Pat. No. 4,244,060, issuedto Hoffer on Jan. 13, 1981, and this discussion is hereby incorporatedby reference.

Many of the early designs for intracapsular lenses were positionedwithin the anterior chamber of the eye. These devices were frequently ofthe type known as an iris clip lens, since the lens was clipped to theiris by pairs of projections which extended on opposite sides of theiris when the lens was in place. Examples of these anterior lenses arediscussed in the Hoffer patent. Additional examples include the lensesdisclosed in the following U.S. Pat. Nos. 3,673,616, issued to Federovet al. on July 4, 1972; 3,996,626, issued to Richards et al. on Dec. 14,1976; 3,996,627, issued to Deeg et al. on Dec. 14, 1976; 3,925,825,issued to Reykers on Dec. 16, 1975; and, 4,079,470, issued to Deeg etal. on Mar. 21, 1978. A related type of lens is disclosed in U.S. Pat.No. 4,014,049, issued to Richards et al. on Mar. 29, 1977, which lens ismounted in the posterior chamber but is secured to the iris.

The prior art also discloses a variety of intraocular lenses which aredesigned for mounting within the posterior chamber. There is disclosedin the Hoffer patent, for example, a lens which is stated to beparticularly adapted for implantation in the posterior chamber afterextracapsular cataract extraction. The Hoffer lens includes severallens-centering filaments which extend outwardly in a common plane fromthe rim of the lens body. These filaments are inserted within the cleftof the capsule to secure the lens within the eye and to center the lensbehind the pupil.

The Hoffer lens also includes an annular lip which projects from therear face of the lens body and is intended to seat against the posteriorcapsule. At least one opening in the annular lip is provided to permitthe insertion of a discission instrument therethrough and into the spacebehind the lens. The Hoffer patent further notes that the lip limits theprogress of vitreous humor toward the anterior chamber after adiscission, and may limit lens fiber growth on the posterior capsulewithin the lip region.

A related intraocular lens is now shown in promotional literature ofCILCO, Inc. of Huntington, W. Va. and is said to be available under thedesignation "HOFFER RIDGE LENS." This lens includes a body portion whichhas a convex front surface and a planar rear surface. An annular ridgeextends rearwardly from and perpendicular to the rear surface adjacentthe periphery of the lens. Instead of having several fine filaments asin the patent, the HOFFER RIDGE LENS includes only a pair of curvedfilaments, probably of greater thickness than those contemplated in thepatent, and which extend outwardly from the lens body at diametricallyopposed locations. Each filament extends nearly tangentially from thelens body and, in one version they curve in a "J" configuration, withthe bottom of the "J" being positioned for seating the lens within theposterior chamber. Another version uses a "C" configuration.

In U.S. Pat. No. 4,110,848, issued to Jensen on Sept. 5, 1978, there isalso disclosed an intraocular lens for implantation into the posteriorchamber of the eye. The Jensen lens includes a pair of loops whichextend outwardly from opposite sides of the lens body at a slightrearward angle. One of the loops includes a notch disposed between itsend portion and the peripheral edge of the lens body so that a temporarysecurement to the iris of the eye may be accomplished.

Another posterior chamber lens is available from Intermedics IntraocularInc. of Pasadena, Calif. under the designation "LESTER POSTERIOR CHAMBERINTRAOCULAR LENS." The LESTER INTRAOCULAR LENS includes a lower orinferior closed loop which extends from the lens body and also an upperor superior J-shaped filament extending from the lens body. The superiorfilament includes a positioning notch located slightly inward of thebase of the "J" shaped filament and opposite the free end of thefilament. The LESTER INTRAOCULAR LENS also includes a single, smallpositioning hole slightly inward of the top edge of the lens body.

Currently available are two lenses which include outwardly extendingfilaments which have closed loops on the ends of the filaments. One suchlens is known as the "PANNU LENS" and is marketed by American MedicalOptics. A second lens having the closed loop at the end of a mountingfilament is available from IOLAB under the designation "OSHER LENS."Neither of these lenses includes a centering notch on the filament.There is a Knolle PC-80 lens which has two filaments, one at the top andone at the bottom, with a depression or notch in one side of eachfilament loop.

Various other devices and techniques have been developed in conjunctionwith intraocular lenses intended for mounting within the posteriorchamber. Lenses including other configurations for the mountingprojections of the lens are disclosed in U.S. Pat. Nos. 4,251,887,issued to Anis on Feb. 24, 1981; 4,092,743, issued to Kelman on June 6,1978; and 3,906,551, issued to Otter on Sept. 23, 1975. A method forimplanting an intraocular lens is described in U.S. Pat. No. 4,159,546,issued to Shearing on July 3, 1979.

SUMMARY OF THE INVENTION

Briefly describing one aspect of the present invention there is providedan intraocular lens for mounting within the posterior chamber whichcomprises a lens body having a convex front surface and a planar backsurface, the lens body including an integral ring extending rearwardlyfrom the back surface. The lens also has a plurality of holes adjacentthe ring. Resilient filament members are attached to and extend from thelens body at diametrically opposed positions. Each of the filamentmembers includes an inward niche and terminates in a closed loop.

It is an object of the present invention to provide an intraocular lensadapted for implantation within the posterior chamber.

Another object of the present invention is to provide an intraocularlens which is readily implanted within the posterior chamber, andparticularly which includes a variety of design features to facilitatehandling, implantation and adjustment of the lens.

It is a further object of the present invention to provide anintraocular lens which is constructed to fit correctly within theposterior chamber and provide a relatively large area of the rear of thelens free of contact with the posterior capsule.

Another object of the present invention is to provide an intraocularlens which facilitates the further treatment of the eye either by readyremoval of the lens or by procedures performed with the lens remainingwithin the eye, such as light frequency or laser capsulotomy, forexample.

Further objects and advantages of the present invention will becomeapparent from the description of the preferred embodiment which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side, sectional view showing an intraocular lens accordingto the present invention implanted within the posterior chamber of aneye.

FIG. 2 is a front, elevational view of an intraocular lens constructedin accordance with one embodiment of the present invention.

FIG. 3 is a rear, elevational view of the lens of FIG. 2.

FIG. 4 is a side, elevational view of the lens of FIG. 2.

FIG. 5 is a front elevational view showing a second and preferredembodiment of the present invention.

FIG. 6 is a side elevational view of the preferred embodiment.

FIG. 7 is an enlarged sectional view taken at line 7--7 in FIG. 5 andviewed in the direction of the arrows.

FIG. 8 is a rear view of the preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiment illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Referring in particular to the drawings there is shown an intraocularlens 10 constructed in accordance with the preferred embodiment of thepresent invention. The lens 10 is particularly adapted for implantationwithin the posterior chamber of the eye. The lens includes a pair ofresilient filament members 11 and 12 which are attached to and extendoutwardly from a lens body 13.

A human eye 14 includes an iris 15 which separates the interior into ananterior chamber 16 and a posterior chamber 17. The lens of the eye issupported within the posterior chamber by the suspensory ligaments orzonules 18 extending from the ciliary muscle in the eye wall region 19.Upon extracapsular extraction of the lens, there remains intact theposterior capsule 20 of the lens, along with an annular flap portion 21of the anterior capsule. As shown in FIG. 1, the intraocular lens 10 ispreferably implanted within the capsular bag 22 between the posteriorcapsule 20 and the flap 21. Alternatively, the lens may be implantedwith the filament members received within the ciliary sulcus 23.

The intraocular lens has a generally disc-shaped lens body 13 includinga convex front surface 24 and a planar back surface 25. The lens bodymay be provided in a variety of dioptric powers, typically ranging from10 to 26. The diameter of the lens body may vary as required, andpreferably is about 7.0 mm. The use of 7 mm. optics and interior bevelto be described reduces the possibility of glare and distortion ofvision as compared to smaller diameter lenses.

The lens body 13 has an integral ring 26 extending rearwardly from theback surface 25. The ring 26 preferably forms a closed circle having apreferred diameter of about 7.0 mm. The ring has a preferred thicknessor width from side-to-side of about 0.50 mm. The ring is generallycircular in cross section as shown in FIG. 4. It is positionable againstthe posterior capsule 20, as shown particularly in FIG. 1. and therebyspaces the back surface 25 of the lens away from the posterior capsule adistance substantially equal to the height of the ring, i.e. 0.25 mm.where the height of the ring is 0.25 mm.

The presence of this ring displacing the lens anteriorly, and providinga space between the planar back surface 25 of the lens body and theposterior capsule, permits improved efficiency of posterior capsulotomyprocedures by laser technique. The YAG Laser, for example, may bereadily used in conjunction with the intraocular lens of the presentinvention with the lens remaining in place during the posteriorcapsulotomy. The spacing of the back surface of the lens body from theposterior capsule reduces the possibility of pitting, cracking orfracturing of the lens which could otherwise occur if the laser is notprecisely focused on the posterior capsule.

The lens body further includes four holes, such as 27 and 28, locatedproximate to the ring and substantially equally spaced about the portionimmediately radially inward from the ring. The holes extend from thefront surface 24 to the back surface 25, and are provided to facilitatepositioning and rotation of the lens after implantation within the eye.Placement of the holes substantially at the four, cardinal positionsshown in the drawings provides maximum convenience for use of the holesin positioning the lens. The holes preferably have a diameter of lessthan about 0.25 mm., with this small size being desirable to reduce thepossibility of glare which may otherwise be produced.

According to another feature, an internal bevel as at 39 (FIGS. 3 and 4)is provided on the ring from the rear lens face 25 out to a locationnear the plane of the rearward surface of the ring. It blends into therest of the generally circular cross sectional shape of the ringimmediately ahead of this plane. This bevel may be at an angle "A" of 60to 85 degrees from the plane of the lens face 25.

The lens 10 also includes a pair of resilient filament members 11 and12. Such members associated with intraocular lenses are sometimes called"haptics". The lens body 13 includes a pair of front bosses 30 and 31which are located forwardly of the back surface of the lens body, andwhich extend outwardly of the front surface. Each front boss includes anaperture within which the proximal end of one of the filament members isreceived and secured. Use of the bosses on the front surface enables thelens body to have a reduced thickness and weight. The filament membersextend from the bosses at a forward angle of about 10° to the plane ofthe back surface (FIG. 4). The invention is not limited to this angle,as it will work even if the filaments are parallel to the plane of theback surface. Rear bosses can be seen in FIG. 3. These cooperate withthe front bosses to accommodate the proximal ends of the filaments. Theabove-mentioned bevel is continued on these rear bosses.

Each of the filament members is formed identically with the other in thefollowing configuration. The filament members project from the lens bodyin a curve having a first part 32 and a second part 33. In the free,unstressed condition of the filament members, the first part 32 of thecurved filament member extends at a progressively increasing radiallydistance from the center of the lens body. The second part 33 of thecurved filament member extends generally concentrically with the lensbody at a substantially constant radius.

Each filament member further includes a niche, such as 34, which isuseful during insertion of the lens into the posterior chamber. Theniche 34 is located along the filament member other than within thefirst part of the curve, and preferably is located at about the junctionof the first and second parts of the curve.

In particular, the niche is preferably located at a position at orslightly more than about 90° from the radial line, such as 35, whichextends perpendicular to the direction of the proximal end of thefilament member. Correspondingly, the first part of the curved filamentmember extends about the lens body at least about 90°. For example inFIG. 2, the proximal end of filament member 11 extends vertically in thedrawing and the radial line 35 extends horizontally, or perpendicular tothe proximal end. The vertical, or meridian radial line 36 is 90° fromthe line 35 and the niche 34 is positioned on or slightly to the rightof the line 36. This positioning of the niche is more anatomicallycorrect in use of the intraocular lens. Heretofore, notches have beenused which are located in the lateral surface of the filament. Accordingto my invention, the niches, being U-shaped and located at the junctureof the two bends in filament and placed on or adjacent the meridian ofthe lens, makes compression of the filament more uniform and facilitatesthe insertion of the implant without the possible slippage of theinserting instrument. This placement of the niche provides for a morestable manipulation of the lens unit during insertion in the eye.

The distal end of each of the filament members is spaced apart from thelens body, and forms a closed loop, such as 37. These closed loops areparticularly beneficial in several respects. First, they preventcatching of the iris or perforation of the posterior capsule by thefilament. Also they aid in uniplanar positioning of the lens in theposterior capsule. That is, it is desirable that both filaments aresituated in the posterior capsule, rather than having one remain in theciliary sulcus. While it is most desirable that both be in the capsule,it would be better to have both in the ciliary sulcus than one there andone in the capsule. Otherwise tilting or "torque" of the lens canresult, and that is undesirable. The filament members of this embodimentpreferably extend over to at least as far as about the edge of the lensbody opposite the location of attachment of the filament member to thelens body. For example, in FIG. 2 the filament member 11 is attached tothe lens body 13 at the left edge, and the filament member extends tothe right beyond the right edge of the lens body.

The filament members extend outwardly of the lens body to have anoverall span somewhat greater than the space within which the lens is tobe implanted. The filament members are formed of a resilient material,suitable for implantation, which permits the members to be flexedinwardly to facilitate insertion into the posterior chamber. Thisresiliency also results in the filament members expanding outwardlywithin the posterior chamber to seat within and bear against thecapsular bag or ciliary sulcus. The filament members thereby secure thelens within the posterior chamber in the desired position. The filamentmembers may have a variety of overall spans to accommodate various sizesand shapes of eyes, and typically would have a span of about 14.25 mm.The substantial span decreases the possibility of the lens decenteringor moving in larger eyes. The relatively large diameter and thereforeoptical zone of the lens body, preferably about 7.0 mm. in diameter,also operates to minimize optical effects resulting from decentration.

As described, the intraocular lens of the present invention isconveniently configured to facilitate its handling, implantation, andadjustment, as well as fitting properly within the posterior chamber.The niches and loops are located in proper position to permit a correct,convenient and stable positioning of the filament members. The identicalconfiguration and opposed placement of the pair of filament members,including particularly the positioning of the niches and closed distalloops, ensures a balanced design for the lens.

The intraocular lens 10 of the present invention is implanted into theposterior chamber in accordance with the following general technique. Anincision is made around a portion of the periphery of the cornea 38 andthe pupil is dilated. The iris is depressed slightly to permit the lowerfilament member to be inserted, preferably into the capsular bag, oralternatively into the ciliary sulcus. The other filament member is thenguided into position opposite the first filament member and the lens isrotated or otherwise adjusted to the final, desired position. Inperforming these steps, any suitable combination of the niches, distalclosed loops or adjusting holes provided for the lens may be used tofacilitate manipulation of the lens into and within the eye. Upon finalpositioning of the lens within the posterior chamber, the resilientfilament members will properly hold the lens body in a centered locationposterior to the iris.

The components of the lens body and filament members may be formed froma variety of materials suitable for implantation, and which provide thenecessary physical characteristics to the component. Various clearplastics, such as polymethyl methacrylate, are known to be useful forformation of a lens body of the type used in the present invention. Thefilament members may similarly be formed from materials and incross-sectional thicknesses known to be useful in this type ofapplication including, for example, polypropylene. It is now possible tomake an entire unit, including not only the lens body but also thefilaments, as a single homogeneous unit of polymethyl methacrylate, andstill do the flexing of the filaments as needed during implantationprocedure, without cracking the filaments. An example of this is presentin the preferred embodiment shown in FIGS. 5 through 8 herein where allof the above-mentioned bosses are eliminated.

Referring now to FIG. 5, the lens 41 has the two filaments (haptics)shown by solid lines in the unstressed, relaxed condition. It has aseven millimeter diameter optic portion to the outer marginal edge 42.In the free, unstressed state, the filaments extend to an outer circle43 of 14 millimeters diameter. The filaments are of one integralhomogeneous mass of material with the optic and extend from twodiametrically opposed locations on the lens.

Filament 44 includes what may be referred to as a first portion "A"which begins tangent the optic at 47 and continues to a "knee" 48. Asecond portion "B" extends from the knee 48 to a knee 49. A thirdportion "C" extending from knee 49 through knee 51 includes the niche52. The fourth portion extends from the end of the third portion tangentcircle 43 to the end loop 55 having a central aperture 53 locatedapproximately 2.40 millimeters from the peripheral edge 42 of the optic.

Since most eye surgeons are right-handed, and it is desirable toslightly rotate the lens following placement of the filaments in thecapsular bag 22, the filaments in this lens are generally curved in acounterclockwise direction (viewed from the front of the lens) as theyextend outward from the lens. They have a diameter of about 0.15millimeters, except at the end loops which are 0.15 millimeter thick buthave a 0.375 millimeter radius about the axis of apertures 53. Thecombination of the third portion "c" of the filament and that part ofthe fourth portion extending from the third portion to a radius 56 fromthe lens axis 57 to the axis of the loop aperture 53, subtends an angleof 30° with respect to the radial line 58.

The first portion of the filament is arcuate about a center at 62 on aline 59 extending through two of the four positioning apertures 61 andthe lens axis, and has a radius of between 9.30 and 9.50 millimeters.The second portion "B", is also arcuate, having a center at point 63located 0.47 millimeters up from line 59 and 0.75 millimeters to theleft of line 58. It has a radius of between 6.15 and 6.35 millimeters.Both the knees 49 and 51 at the ends of the third portion are tangent acircle about center 63 defining the arc of the second portion "B". Theradius of the arc of the fourth portion is 1.10 to 1.30 millimeters andcentered at point 64. The radius of the niche 52 is preferably 0.30 to0.50 millimeters. This is the preferable radius also at the inside ofthe knees 49 and 51 and at the location 66. The loop apertures 53 are ofthe same 0.25 millimeter diameter as are the positioning apertures 60and 61. They are located between 2.25 and 2.55 millimeters from theperipheral edge 42. The radius of the fillet inside the junction of thefilament with the optic at 67 is typically 0.20 millimeters. As bestshown in FIG. 6, each filament is planar and extends outward from theoptic in a plane such as plane 68 at an angle of 10° from the plane 69of the back surface of the ring.

The ring projects to the rear from the flat back surface 71 of the opticand is uniform and homogeneous around its cirumference. It has an innerwall 72 with a draft of 3° and a radius blend at 73 between this walland the back surface 74 of the ring. The diameter of wall 72, andthereby the optic, is preferably between 6.10 and 6.30 millimeters, asgreat as possible consistent with a reasonable area of ring back surfaceand blend at 73 to avoid light reflections at the edge. The depth of thecavity 76 from the plane 69 to the optic back surface 71 is 0.20 to 0.25millimeters. The resulting 0.20 to 0.25 ring height facilitates use ofthe YAG laser, without damage to the lens, as discussed above. Thisheight, together with the continuity and shape of the ring, has theexpected effect of decreasing the migration of germinal cells to theoptical zone of the posterior capsule, thus reducing capsularopacification. The radius of the convex face 77 of the lens depends uponthe lens power needed for the visual performance to be achieved with thelens.

If the lens of this embodiment is placed in the ciliary sulcus of theeye as at 23 in FIG. 1, instead of within the capsular bag 22, it willhave an appearance much as shown in the unstressed state shown in thesolid lines in FIG. 5. The diameter of circle 43 is approximately 14millimeters. If the lens is placed in the capsular bag 22, the filamentsmay be confined within a circle which can vary from 11 millimeter to 12millimeter diameter. The dotted outline in FIG. 5 shows the attitude ofthese filaments when they are confined within a circle of 11 millimeterdiameter. In this instance, instead of the third and fourth portions ofthe filaments being the outermost, it is the second portion which is atthe maximum diameter when the filaments are thus resiliently stressed inthis confinement, and these are tangent the inner wall of the ciliarysulcus. In both attitudes of the "A" filament portion, that shown by thesolid line in FIG. 5 and that shown by the dotted line, a portion of thefilament is proximate the confinement tissue. At the 14 millimeterdiameter, it is the third-fourth portion. In the 11 millimeterconfinement, it is the second portion. At the same time, the adjacentportion is very close to the peripheral confining tissue. In thismanner, regardless of the cavity in which the lens is deposited, withinthe above-mentioned 11 to 14 millimeter limits, these filaments providesomething that simulates a four-point fixation in the eye. This isdifferent from other lens configurations of which I am aware, in that itgives more stability and less torquing in the eye. It also gives lesscontact with the ocular structures but, at the same time, affords goodstability. To avoid clutter in FIG. 5, dotted lines are included in therear view of FIG. 8 to show the more typical attitude of the filamentswhen the circle of the confinement tissue represented at circle 78 inFIG. 8 is about 12 millimeters in diameter. This is the ideal situationand, due to the resilience of the filaments and some compliance of thetissue, the four point contact with tissue as at circle 78 is achievedin many cases.

The holes 53 facilitate maneuvering the lens. The same is true of theholes 60 and 61. The niches at 52 facilitate insertion of the lens intothe superior capsule or bag. The ring provides the desired 0.25millimeter separation between the lens and posterior capsule afterinsertion into the eye and thus facilitate laser capsulotomy ifnecessary at some later time. Meanwhile, because of the expected effectof the continuous ring in reduction of migration of cells across theposterior capsule, opacification of the capsule should be reduced andthe necessity for capsulotomy postponed or avoided. The lens is veryflexible, having a somewhat linear force/compression characteristic suchas 0.13 grams for 0.5 millimeter, 0.3 grams for one millimeter, and amaximum force of approximately one gram to achieve a three millimetercompression distance.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected. The terminology "front" and "back" and"forward" as used in claims hereinafter, is intended to establishrelationships in the lens itself, but not be construed as limitationswith respect to whether it is "front" or "back" when in the eye in whichit is to be used.

The invention claimed is:
 1. An intraocular lens for implantation withinthe eye, said lens comprising:a lens body having a central axis and aback surface and a convex front surface; and a pair of resilientfilament members extending outwardly from said lens body atsubstantially diametrically opposed positions, each of said filamentmembers having a proximal end at said lens body and a distal end spacedapart from said lens body, each filament member including an inwardniche having a depth greater than the thickness of the filament memberand located intermediate the proximal and distal ends, each of saidfilament members projecting from said lens body in curves having a firstpart and a second part, the first part extending at a progressivelyincreasing radial distance from said axis of said lens body, the secondpart extending generally concentrically with said lens body, thefilament members being shaped and the niches located to provide fourpoint fixation of the lens in the confinement tissue of the eye.
 2. Thelens of claim 1 in which each of said filament members includes theniche located outboard of the first part of the curves and at a distancefrom the lens body such that, when the filament members are confinedwithin any confinement circle centered on said axis and having adiameter between 11 and 13 mm., the filament members are resilientlydeformed and each filament member is resiliently urged outward intocontact with the confinement circle at a first point on at least oneside of the niche while a second point on the opposite side of the nicheis less than the said niche depth away from said confinement circle, tothereby provide four point fixation of the lens in the eye when thefilament members resiliently engage tissue in the eye.
 3. The lens ofclaim 2 in which each of said filament members includes the nichelocated at the junction of the first and second parts of the curves ofsaid filament member.
 4. The lens of claim 2 in which the body has anintegral ring extending rearwardly from the back surface and located atthe periphery of said lens body.
 5. The lens of claim 2 in which each ofsaid filament members extends forwardly from said lens body at an angleof about 10° to the back surface of said lens body.
 6. An intraocularlens for implantation within the eye, said lens comprising:a lens bodyhaving an axis, a back surface and a front surface, said front surfacebeing convex; a pair of resilient filament members extending from saidlens body to substantially diametrically opposed locations, each of saidfilament members being resiliently deformable from a free, relaxedconfiguration and condition, to a contracted condition to facilitateinsertion into a chamber of an eye adjacent the pupil, each filamentmember in the free, relaxed configuration having a first portionextending outwardly from a perimetrical location on the lens body, asecond portion having an arc extending circumferentially about a centeradjacent the lens axis, third, fourth and fifth portions in sequencefrom said second portion, said third portion being an inward niche, saidfourth portion having a radius substantially less than the radius ofsaid arc, and said fifth portion being a distal end portion with a loopat the distal end, whereby the filament members are adapted toresiliently engage confinement tissue in the eye at four points, saidpoints being at the second and fourth portions of each filament memberon opposite sides of the niche to establish four-point fixation of thelens in the eye.
 7. The lens of claim 6 wherein:the lens body iscircular about said axis and has a diameter between 6.80 and 7.20millimeters; and with the filament members in the free unstressed state,said center of said second portion is offset from said lens axis atleast 0.37 millimeters; and the radius of said arc is between 6.05 and6.45 millimeters.
 8. The lens of claim 6 wherein, with the filamentmembers in the free unstressed state:said fourth portion is tangent acircle centered on said axis and having a diameter between 13.90 and14.10.
 9. The lens of claim 8 wherein:said second portion begins insidesaid circle and said distal end loop is inboard of said circle.
 10. Thelens of claim 9 wherein:said distal end loop is an aperture in thefilament member less than 0.375 millimeter diameter and located between2.25 and 2.55 millimeters from said body.
 11. The lens of claim 10wherein:said third, fourth, and fifth portion to said aperture subtendan angle about said axis of less than 30°.
 12. The lens of claim 6whereineach of said filament members is shaped into a knee bend joiningsaid first and second portions, and two knee bends in said thirdportion, one joining said second portion and the other joining saidfourth portion.
 13. The lens of claim 12 wherein:said first portions arecurved, having a radius of between 9.30 and 9.50 millimeters and extendtangentially from the edge of said body.
 14. The lens of claim 13wherein:said members have a generaly circular cross section with adiameter of between 0.12 and 0.18 millimeters.
 15. The lens of claim 14wherein:the material of said body and members is one homogeneous unit ofpolymethylmethacrylate.
 16. The lens of claim 15 wherein:both of saidmembers curve around said lens body from said body outward in acounterclockwise direction, as viewed from the front of the lens.